2706.     ---------------.  [PINGAULT, P.]  [Cementite.]  Ann. chim., vol. 20, 1933, pp. 371-438; Chem. Abs., vol. 28, 1934, p. 3040.

                    Cementite (Fe3C, 6.65-6.70%) containing 0.05% of free C was prepared by heating Fe with NaCN at 600°-650°; it also may be prepared by electrolysis of fused NaCN with Fe electrodes or by passing coal gas or CH₄ over Fe at 850°-975°.  Fe₃C reduced by H₂ has a density at 0° of 7.30, is not attacked by H₂ under atmospheric pressure at 450°, is thermodynamically unstable at ordinary temperatures, and begins to decompose near the melting point of cast Fe.  The equilibria in the system Fe-Fe₃C-O₂ have been studied at 830°-1,000°.

                       ----------.  See abs. 472.

          PINKEL, I. I.  See abs. 3295.